Global warming of surface air temperature is largely due to increases in greenhouse gases, which lead to increased radiative heat fluxes toward Earth’s surface. While changes in radiative heat fluxes are known to contribute to surface warming, changes to ocean circulation can also impact the rate of surface warming. Previous studies suggest that projected changes to ocean circulation reduce the rate of global warming. However, the relative contribution of different ocean processes (wind-driven circulation, density, etc.) has not yet been explored.
In a new Geophysical Research Letters article, authors Kay McMonigal, Sarah Larson, Shineng Hu, and Ryan Kramer use a climate model to quantify the role of changes to the wind-driven ocean circulation onto global air temperature warming.
Surface air temperature anomalies, with red showing Fully Coupled Mode and blue showing Mechanically Decoupled Model. Thick lines are ensemble means. Shading shows 2 standard deviations across ensemble members. The thick black line shows the GISTEMP observational product. Right-hand side histograms show the trend over 1979–2015 multiplied by the time period, to yield the change of each field.
It was found that wind-driven ocean circulation played a critical role in pacing the global warming rate over 1979–2014; amplifying global warming by 17% during that timeframe. The authors note that climate models need to adequately simulate changes to the winds, and the ocean’s response to these wind changes, to accurately project climate change.
This study was partially funded by the MAPP program.
Read the full paper here.
The Modeling, Analysis, Predictions, and Projections (MAPP) Program is a competitive research program in NOAA Research’s Climate Program Office. MAPP’s mission is to enhance the Nation’s and NOAA’s capability to understand, predict, and project variability and long-term changes in Earth’s system and mitigate human and economic impacts. To achieve its mission, MAPP supports foundational research, transition of research to applications, and engagement across other parts of NOAA, among partner agencies, and with the external research community. MAPP plays a crucial role in enabling national preparedness for extreme events like drought and longer-term climate changes. For more information, please visit www.cpo.noaa.gov/MAPP.